developing and deploying ptp now. - nist · case study 2: network and requirements pdv + freq...
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Developing and deploying
PTP now.Tommy Cook,
CEO
www.calnexsol.com
Synchronisation hot-topics over the last year:
What’s driving innovation?
� Detailed investigation into delivery of Time/Phase.
– Using T-BCs with/without SyncE .
– Using T-TCs.
� Need for support of Partial On-path support topologies.
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� Need for support of Partial On-path support topologies.
� Discussion on the needs of Small Cells & Small Cell clusters.
– More bandwidth through more complex technologies.
� Proof of Concept trials by Operators.
Hot Topic: Time/Phase delivery
Basics
Frequency: G.826x Time/Phase:G.827x
G.8261.1
(NetwkPDV_frequency)
G.8271.1
(NetwkPDV_time/phase)Network
requirements
SyncE Jitter-Wander:
(Included in G.8261)
G.8261 G.8271
G.8271.2?
Definitions /
terminology
G.8260
(Definition)G.8260 App.
(metrics)
ITU-T Sync recommendations
Under
Development
Agreed
07-201307-2013
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G.8265.1
(PTP Profile 1)G.8275.1
(Full on-path support)
Clock
Methods
Profiles
G.8265.m
(PTP Profile m)
(NetwkPDV_frequency)
G.8272
PRTC
G.8275
(architecture-time)
G.8262
(SyncE)
G.8264
(SyncE-architecture-SSM)
G.8265
(architecture-Frequency)
G.8275.2
(Partial on-path support)
73.1 GM
73.2 BC
73.3 TCG.8263
(slave clock) 73.4 ?
G.8273
07-201307-2013
07-201307-2013
07-201307-2013
20142014
07-201307-2013
07-201307-2013
03-201403-2014
G.8275.1 - 1588v2 for Phase/Time
CORE
PTP
ACCESS AGGREGATION EDGE
BC/TC
BC/TC
PTP
MPLS
Cell Site
Routers
BC/TC/Slave
Carrier
Ethernet BC/TC/Slave
Slave
PRTC
1588v2 GMPTP
PTP
BC/TC
P-OTN or
MPLS or
EoS
BC/TC
BC/TC
BC/TC
BC/TC/Slave
TC
xDSL, etc.)
Slave
SlaveμWave
P-OTN or
MPLS or
EoS or
Carrier Ethernet PTP
PTPPTP
BC/TC
BC/TC
Boundary Clock
Boundary Clocks reduce PDV
accumulation by;
• Terminates the PTP flow and
recovers the reference timing.
• Generate a new PTP flow
using the local time reference,
(which is locked to the
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(which is locked to the
recovered time).
• No direct transfer of PDV from
input to output.
Boundary Clock is in effect a
back-to-back Slave+Master.
• Optionally can utilise SyncE
for frequency transfer.
Sla
ve
Ma
ste
r
Time/Phase
(1pps)
Frequency
(T1/E1/SyncE)
Transparent ClockTransparent Clocks reduce PDV by;
• Calculating the time a PTP packet resides in the
TC device (in nsec) and insert the value into the
correctionField.
• By using the correctionField, the Slave or
terminating BC can effectively remove the PDV
introduced by the TC.
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Q1
Q2
Qn
Packet Delay in TC Device
inserted into correctionField
at output of Transparent Clock device
• Can also be transferring SyncE in the Physical
layer. SyncE will have less benefit to T-TC
performance compared to T-BC performance
case as ‘just’ packet latency measured, which
can be done with a good local oscillator.
Networks with ‘1588v2 aware’ switches
• The ‘G.81x approach’ offers a Standards-based structured, bottom-up approach.
• The performance of each device in the path is know and has been proven.
• Adhere to topology guidelines and the resulting network performance will be
within defined performance limits.
• With full On-path support of 1588v2 aware switches, it should be possible to deliver
packet networks using a ‘G.81x approach’.
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• Work on-going in ITU-T SG15, Q.13 to simulate networks of BCs with the objective
of specific performance requirements of individual and chains of BCs.
• Once specifications are in place, then BCs &/or TCs can be qualify and provided
the guidelines to building networks is adhered to, it should be possible to build
timing networks using the principles used in the past and aligned to those well
proven in the ‘G.81x approach’.
PTPMaster
~
PTPSlaveTC TC TC
PoC: Network Evaluation for Full On-path Support
• Evaluate each 1588v2 aware device.
• T-BC: Time Noise Generation, Time Noise Tolerance, Time Noise Transfer, etc.
• T-TC: Accuracy of correctionField.
• Evaluation of networks of devices
• Verification of error accumulation through chains of devices.
• Verification of Slave performance when stressed with ‘accumulated error’.
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• Verification of Slave performance when stressed with ‘accumulated error’.
• Future: Performance specified in ITU-T Standards e.g. G.8273.2 for T-BC.
Today: Perform Lab Evaluation to develop deployment plan.
PTPMaster
~
PTPSlaveTC TC TC
PoC: T-BC Noise Accumulation trial
Node
A
Node
B
Node
C
Node
D
Evaluate T-BC nodes & Slave
Slave
PTPMaster
~
Time/Phase Time Error Accumulation
• Compare multiple T-BCs & Slave in a chain.
• Trial dependent on expected deployments.
• Different or all the same manufacturer?
• Develop rules for your network.
Time/Phase Time Error Accumulation
• Compare multiple T-BCs & Slave in a chain.
• Trial dependent on expected deployments.
• Different or all the same manufacturer?
• Develop rules for your network.
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Frequency
Phase
ToD
Frequency
Phase
ToD
Frequency
Phase
ToD
Frequency
Phase
ToD
Frequency
Phase
ToD
Hot Topic: Partial On-path
Partial On-path Support
G.8275.2: The second ITU-T Time profile will specific Partial On-path support
networks for Time transfer.
• Operators, lead by US Operators (AT&T, Sprint, Verizon) highlighting to ITU-T
Q.13 the practical need for a set of documents to define the use of Partial
On-path Support.
• Not practical for all nodes to be T-BCs or T-TCs every time 1588v2 is
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• Not practical for all nodes to be T-BCs or T-TCs every time 1588v2 is
transported across a network.
• Definition work underway in ITU-T Q.13.
How many T-BC/T-TCs do I need and where do I put them?
PTPMaster
~
PTPSlave
PoC: Partial On-path support
PTPMaster
~
PTPSlave
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Time/Phase Time Error Accumulation
• Evaluate sub-network combinations to develop rules for
‘how many?’ and ‘how often?’
• Evaluate performance of each 1588v2 aware device.
• Evaluate networks of devices aligned to expected
topologies.
• Develop rules for your network.
Time/Phase Time Error Accumulation
• Evaluate sub-network combinations to develop rules for
‘how many?’ and ‘how often?’
• Evaluate performance of each 1588v2 aware device.
• Evaluate networks of devices aligned to expected
topologies.
• Develop rules for your network.
Hot Topic: Small Cells
• Increase capacity and coverage in high usage pockets
• Town Centres, Shopping Malls, Sports
arena, Business parks, etc.
• Benefits• Increase capacity
• Offload congested Macro cells
• Densify coverage
The Need for Small Cells
Wireless Mesh
Wireless
Macro Site Router
• Densify coverage
• Deployment method• Wirelessaccess
• Fibre access
• Technology proliferation
• eICIC, MIMO, CoMP, etc.
• Frequency & Phase/Time sync required• Delivered through wireless links
• Tight requirement necessary especially
for new technologies
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Macro Site Router
Baseband Processing
Wireless
Point to
Multi-point
Dedicated
Fibre (CPRI)
PoC: Case Studies - Network Trials
Case Study 1: Network and Requirements
• Network A: Carrier Ethernet & SDH
• Network B: Carrier Ethernet
• Network C: Carrier Ethernet
NTP
Server
GPS
PDV
Monitor
GPS/Rb
Node B
NTP Client
Requirement A
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Node B requirements:
• The Node B will lock within a 16 minute period if either
a) 1% of packets within 20µsec of Noise Floor, or
b) 99% of packets with <0.3msec spread.
• If case b) is greater than 0.3msec, then
• If 99% with <3msec spread, will lock
within 60 minutes.
• If 99% with <10msec spread, will lock
within 180 minutes.
Requirement B
11msec
20µsec
For 16 min Lock, either
a) 1% within 20µsec, or
b) 99% with <0.3msec spread.
For 60min Lock,
• If 99% with <3msec spread
Network A Results NTP
Server
GPS
Carrier Ethernet
& SDHPDV
Monitor
GPS/Rb
Node B
NTP Client
Result A: 1% in 20µsec, FAIL Result B: 99% in 0.3msec spread, Result C: 99% in 3msec spread, PASS
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Requirement BRequirement A
Result A: 1% in 20µsec, FAIL Result B: 99% in 0.3msec spread,
FAIL
Result C: 99% in 3msec spread, PASS
260µsec260µsec
20µsec
For 16 min Lock if either
a) 1% within 20µsec, or
b) 99% with <0.3msec spread.
For 60min Lock,
• If 99% with <3msec spread
Network B Results NTP
Server
GPS
Carrier Ethernet PDV
Monitor
GPS/Rb
Node B
NTP Client
Requirement A
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Requirement B
Result A: 1% in 20µsec, PASS Result B: 99% in 0.3msec spread, PASS
Case Study 2: Network and Requirements
Three different routes through the
network.
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PTP Client Frequency output to
meet G.8261.1 MTIE Mask
PDV + Freq PDV + Freq
Monitor
510µsecTest 1: Re-route
Case Study 2: Network and Requirements
PDV + Freq PDV + Freq
Monitor
test GM Site Number of
Nodes
Max Sync PDV
(s)
G.8261.1
MTIE mask
Field Test 1 SSU BNH n/a 0.000 550 285 FAIL
Field Test 2 SSU BNH n/a 0.000 438 685 PASS
Field Test 3 SSU HNI 11 0.014 638 985 PASS
Field Test 4 SSU BNH 8 0.000 111 775 PASS
Field Test 5 SSU HNI 7 0.016 397 735 PASS
Field Test 1
510µsec
215µsec
Test 1: Re-route
caused step change
11mins
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Field Test 2
Case Study 2: Network and Requirements
PDV + Freq PDV + Freq
Monitor
test GM Site Number of
Nodes
Max Sync PDV
(s)
G.8261.1
MTIE mask
Field Test 1 SSU BNH n/a 0.000 550 285 FAIL
Field Test 2 SSU BNH n/a 0.000 438 685 PASS
Field Test 3 SSU HNI 11 0.014 638 985 PASS
Field Test 4 SSU BNH 8 0.000 111 775 PASS
Field Test 5 SSU HNI 7 0.016 397 735 PASS
Field Test 4
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Field Test5
Summary – What is driving innovation?
Phase/Time & Frequency Deliver in tomorrow’s networks
• Deliver of Time & Phase with Standards compliance.
• G.8275.1 Full-on Path support
• G.8275.2 Partial On-path support.
• The need for Partial On-path support will drive innovation to achieve the
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• The need for Partial On-path support will drive innovation to achieve the
required performance.
• The need for Frequency & Phase delivery to Small cell clusters utilising new
technologies (e.g. MIMO, CoMP) necessary for proliferation of mobile access.
• Experiences from PoC trials will impact the industry direction & speed of
progress.
• Enable deployments prior to Standards availability.
• Enable quantitative comparisons between devices.
• Enable development of depolyment rules, e.g. address the ‘how many? & ‘how often?’
questions.
CALNEXSOL.COM
Tommy Cook
tommy.cook@calnexsol.comtommy.cook@calnexsol.com
+44 (0) 1506-671-416
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